Solid reaction products of lower alkyl decaboranes and alkyl cyanides



3,030,407 Patented Apr. 17,1962

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nite tates soLro REACTION P oDIJcTs F LOWER ALKYL DECABORANES AND ALKYL CYANIDES I Edmond L. Graminski, Butfalo, and .William L. Wachtel,

Niagara Falls, N.Y., assiguors to Olin Mathieson' Chemical Corporation, a corporation of Virginia. No Drawing. Filed July 29, 1958, Ser. No. 751,804 11 Claims. (Cl. 260465.1)

This invention relates to solid reaction products of lower alkyl cyanides and lower alkyl decaboranes.

The solid products of this invention when incorporated with suitable oxidizers such as ammonium perchlorate,

potassium perchlorate, sodium perchlorate, ammonium the performance of a propellant charge is the specific 'alkyl group containing from 1 to 4 carbon atoms, are

prepared by the direct reaction of the lower alkyl decaborane with the cyanide. In general the reaction temperature can be varied widely from about 50 to 100 C. In a like manner, the molar ratio of alkyl cyanide to alkyl decaborane can be-varied through a wide range, from about 1 toj15z1.

This invention is not restricted to the use of methyl cyanide, and other alkyl cyanides such as ethyl cyanide,

ployed.

Lower alkyl decaboranes can be prepared, for example, according to the method described in application Serial No. 540,141, filed October 12, 1955, of Altwicker et al.

The following examples illustrate in detail the process of this invention. In the examples, the term mole signifies gram mole.

In the examples, the reactions were carried out in a 50 ml., three-necked, round bottomed flask, fitted with a thermometerand a Liebig-Mini-Lab condenser maintained at 80 C. A magnetic stirring bar was used for agitation. The apparatus was connected to a calibrated, high vacuum train through a cold-finger condenser. A gas buret was placed between the reaction vessel and the vacuum system in such a Way that the volume of gas evolved and the rate of gas evolution could be measured. Periodically the gas evolved was bled through the condenser into the vacuum apparatus because the quantity of gas evolved was greater than the capacity of the gas buret. The reactions were carried out atsubstantially atmospheric pressure.

4 Example I Under an atmosphere of nitrogen, 8.3 grams (0.052 mole) of monoethyldecaborane and 5.5 .grams (0.134 mole) of methyl cyanide were dissolved in 40 ml. of benzene in the reaction flask which was then immersed in a heated oil bath. The reaction temperature was maintained between 75 to 80 C. for thirteen hours during which time 0.018 mole of hydrogen was evolved. The

reaction flask was removed from the oil bath, cooled to room temperature, and opened to the high vacuum train. The volatile materials which flashed 011. were analyzed mass spectrometrically and found to be methyl cyanide and benzene.- The yellow semi-solid residue which re mained in the reaction flask was washed with methyl- I I cyclohexane threetimes and then extracted with n-pentane accounted for.

n -propyl cyanide, and n-butyl cyanide can also be emfor 9 hours. It was dried under vacuum and 3.1 grams of an essentially white solid was obtained. Based on the reaction of 2 moles of methylcyanide per mole of monoethyldecaborane, this represented a theoretical yield of 74.3 percent. The product was found to contain 47.2 percent boron. 3.059 grams of methylcyanide were recovered after the reaction and 1.482 grams reacted (based on hydrogen evolved) leaving about 1 gram un- 5.6 grams of monoethyldecaborane were recovered and 2.61 grams reacted, accounting for essentially all of the monoethyldecaborane.

Example II Under an atmosphere'of nitrogen, 10.6 grams (0.0596 mole) of diethyldecaborane and 6.15 grams (0.15 mole) of methyl cyanide were dissolved in 5 ml. of benzene in the reaction flask which was then immersed in the oil bath. The reaction temperature was maintained between 78- 81 C. for 5.5 hours during which time 0.0114 mole of hydrogen was evolved. The reaction flask was removed from the oil bath, cooled to room temperature, and opened to the vacuum train. After the volatile materials had flashed off, the reaction residue, which was a straw yellow viscous gummy oil, was transferred to a dry box. There under a nitrogen atmosphere, the residue was dissolved in about 25 ml. of benzene and 300 to 400 ml. of methylcyclohexane Was added to precipitate the product. The solvents were decanted from the precipitate which was washed several times with methylcyclohexane. The product was dissolved in benzene, precipitated and washed with methylcyclohexane two more times. The washed product was dissolved in benzene and the benzene was removed under vacuum. The resulting orange solid was kept under vacuum for 16 additional hours and then stored under nitrogen. An infrared spectrum of a portion of the orange solid indicated the presence of Water, boric acid, some C-H absorption, and a B- -H absorption similar to that obtained on a yellow solid produced by the pyrolysis of diborane. After exposure to air during analysis, this portion was insoluble in benzene. Another portion of the orange solid was dissolved in benzene and an infrared spectrum of the benzene solution showed similarities to the monoethyldecaborane-methyl cyanide product of Example I with good NH absorption. Analysis of the solid product showed it to contain 40.3, 40,0 percent boron, 34.18, 33.92 percent carbon, 9.61, 9.41 percent hydrogen, and 10.2 percent nitrogen.

Example 111 Under an atmosphere of nitrogen, 8.34 grams (0.0404 mole) of triethyldecaborane and 25 m1. (0.477 mole) of methyl cyanide were placed in the reaction flask which was then immersed in the oil bath. The reaction mixture was heated to methyl cyanide reflux temperature (82 C.) and maintained at a temperature of about 83 C. for 35 hours. Hydrogen was evolved slowly (only 0.0085 mole was obtained during the first 12 hours) and no attempt was made to measure the total amount evolved. The reaction flask was then removed from the oil bath, cooledto room temperature, and opened to the vacuum train. After the volatile materials had flashed off, a dark brown sticky residue remained. The volatile material was found to be methyl cyanide. The dark brown residue was washed with methylcyclohexane until a tan powder remained, which powder was soluble in benzene. Chemical analysis of the tan powder showed it to contain 35.9 percent boron, 33.2 percent carbon, 8.5 percent hydrogen, and 8.3 percent nitrogen.

In a similar experiment wherein the triethyldecaborane and methyl cyanide were dissolved in 25 mil. of benzene, no reaction occurred after heating for 46 hours at refiux temperature.

Example IV Under an atmosphere of nitrogen, 10 ml. (0.0404 mole), of tetraethyldecaborane' and 25 ml. (0.477 mole) of methyl cyanide were placed in the reaction flask which was then immersed in the oil bath. The reaction mixture was maintained at about methyl cyanide reflux temperature for 48 hours during which hydrogen evolved slowly. The reaction flask was then removed from the oil bath, cooled to room temperature, and opened to the vacuum train. After the volatile material had flashed oif, a brown tacky residue remained. This residue was dissolved in benzene and eluted with methylcyclohexane which resulted in isolation of a yellowish powdery solid. Infrared analysis indicated that the product resembled very closely the triethyldecaborane-methyl cyanide product of Example III. Chemical analysis indicated a boron content of 31.2% or intermediate between a diand tri-substituted product (34.4 and 30.5% respectively).

In a similar experiment wherein the tetraethyldecaborane and methyl cyanide were dissolved in 25 ml. of benzene, no reaction occurred after heating for 56 hours at reflux temperature.

The boron containing solid materials produced by practicing the methods of this invention, can be employed as ingredients of solid propellant compositions in accordance with general procedures which are well understood in the art, inasmuch as the solids produced are readily oxidized using conventional solid oxidizers such as ammonium perchlorate, potassium perchlorate, sodium perchlorate and the like. In formulating a solid propellant composition employing one of the materials produced in accordance with the present invention, generally from to 35 parts by weight of boron containing material and from 65 to 95 by weight of oxidizer are present in the final propellant composition. In the propellant, the oxidizer and the product of the present process are formulated in intimate admixture with each other, as by finely dividing each of the materials separately and thereafter intimately mixing them. The purpose of doing this, as the art is well aware, is to provide proper burning characteristics of the final propellant. In addition to the oxidizer and the oxidizable material, the final propellant can also contain an artificial resin generally of the ureaformaldehyde or phenol-formaldehyde type, the function of the resin being to give the propellant mechanical strength and at the same time improve its burning characteristics. Thus, in manufacturing a suitable propellant, proper proportions of finely divided oxidizer and finely divided boron containing material can be admixed with a high solids content solution of partially condensed ureaformaldehyde or phenol-formaldehyde resin, the proportions being such that the amount of resin is about 5 to 10 percent by weight based on the weight of oxidizer and boron compound. The ingredients are thoroughly mixed with the simultaneous removal of solvent, and following this the solvent free mixture is molded into the desired shape, as by extrusion. Thereafter the resin can be cured by resorting to heating at moderate temperatures. For further information concerning the formulation of solid propellant compositions, a reference is made to U.S. Patent 2,622,277 to Bonnell and US. Patent 2,646,596 to Thomas.

We claim:

1. A method for the production of a solid reaction product of a lower alkyl decaborane and an alkyl cyanide which comprises reacting a lower alkyl decaborane with from 1 to 15 moles, per mole of lower alkyl decaborane, of an alkyl cyanide containing from 1 to 4 carbon atoms in the alkyl radical at a temperature within the range from about C. to C.

2. The method of claim 1 in which the alkyl cyanide is methyl cyanide.

3. The method of claim 2 in which the lower alkyl decaborane is monoethyldecaborane.

4. The method of claim 2 in which the lower alkyl decaborane is diethyldecaborane.

5. The method of claim 2 in which the lower alkyl decaborane is triethyldecaborane.

6. The method of claim 2 in which the lower alkyl decaborane is tetraethyldecaborane.

7. The solid products produced by the method of claim '1.

8. The solid products produced by the method of claim 3.

9'. The solid products produced by the method of claim 4.

10. The solid products produced by the method of claim 5.

11. The solid products produced by the method of claim 6.

No references cited. 

1. A METHOD FOR THE PRODUCTION OF A SOLID REACTION PRODUCT OF A LOWER ALKYL DECABORANE AND AN ALKYL CYANIDE WHICH COMPRISES REACTING A LOWER ALKYL DECABORANE WITH FROM 1 TO 15 MOLES, PER MOLE OF LOWER ALKYL DECABORANE, OF AN ALKYL CYANIDE CONTAINING FROM 1 TO 4 CARBON ATOMS IN THE ALKYL RADICAL AT A TEMPERATURE WITHIN THE RANGE FROM ABOUT 50*C. TO 100*C. 